5.
Agricultural - research
has led to healthier livestock and disease-free crops.

I.Microbiology
defined - The study of microbiology is the study of microorganisms, which are
organisms that are invisible to the naked eye.

II.Classification of Microorganisms

The 5 major groups of microorganisms: bacteria, algae, fungi,
protozoa, and viruses.We will also study
some other smaller groups such as prions and viroids.The one property that links these groups together is their very small size!

Important
Note:We will consider a sixth group, the helminths (worms), in our study of microbiology.While most of the adult stages of these worms are
macroscopic, many of them go through a microscopic stage in their life cycles (egg &
larval stages).Some examples of helminths
are tapeworms, hookworms, pinworms, heartworms, and Chinese liver flukes.More to come later!!

III.A Brief History of Microbiology

C.Leeuwenhoeck (lived 1632-1723)

1.What discovery is he credited
with?First person to use microscopes to
observe microbes; as a hobby he made small handheld microscopes; he called microorganisms
animalcules.

C.Hooke

1.What discovery is he credited with?He first described cellulae (small
rooms) in cork in 1665.His discovery
led to the formulation of the cell theory, which states that cells are the basic
organizational unit of all living things.

2.Who disproved this theory and
how?In the late 1600s Francisco Redi showed that maggots developed only
in meat that flies could reach to lay eggs on.

3.Many insisted that he only
disproved spontaneous generation for macroorganisms; maybe microbes were an exception.

D.Needham vs. Spallanzani - still trying
to prove or disprove the theory of spontaneous generation.

1.What was Needham's hypothesis,
experiment, & conclusions?Everyone knew
boiling killed microbes; so, he would boil chicken broth, put it in a flask, & seal
it; if microbes grew, then it could only be because of spontaneous generation; they did
grow.[We now know that microbes grew because
the flask was not sterilized before he poured in the broth!]

2.What was Spallanzani's
hypothesis, experiment, & conclusions?He
was not convinced by Needham's experiment.He
put broth in a flask, sealed it (creating a vacuum), & then boiled it.There were no microbes in the cooled broth!Critics said he didn't disprove spontaneous
generation - they said he just proved that spontaneous generation required air.

E.Pasteur's
Epic Experiments (1859)

1.What was his experimental
method?To offset the argument that air was
necessary for spontaneous generation, Pasteur allowed the free passage of air, but
prevented the entry of microbes.He boiled
meat broth in a flask & then drew out & curved the neck of the flask in a flame.No microbes developed in the flask.When he tilted the flask so some broth flowed into
the curved neck & then tilted it back so the broth was returned to the base of the
flask, microbes grew.Gravity had caused the
microbes that had entered the flask in air & dust to settle at the low point of the
neck, never reaching the broth in the base until the broth washed them in.

2.Pasteur's success was partly
due to good luck.He used meat, which
contains few bacterial endospores (endospores are resistant to heat; many experiments done
prior to Pasteur's used vegetable broths - plants contains many endospore-forming
bacteria.)

3.What 3 things did Pasteur's
experiments prove?

a.No living things arise by
spontaneous generation.

b.Microbes are everywhere - even
in the air and dust

c.The growth of microbes causes
dead plant & animal tissue to decompose & food to spoil (this led him to develop
the technique of pasteurization - he developed
it to keep wine from spoiling).

3.What disease was he studying?anthrax - disease of cattle/sheep; also in humans

4.What was his experimental
method?He observed that the same microbes
were present in all blood samples of infected animals.He isolated and cultivated these microbes (now known to be Bacillus anthracis ).He then injected a healthy animal with the
cultured bacteria & that animal became infected with anthrax & its blood sample
showed the same microbes as the originally infected animals.

1.)The causative agent must be
present in every individual with the disease.

2.)The causative agent must be
isolated & grown in pure culture (how did he invent pure cultures?; with Frau Hesse's
help, he developed the agar plate method (see
p. 13).

3.)The pure culture must cause the
disease when inoculated into an experimental animal.

4.)The causative agent must be
reisolated from the experimental animal & reidentified in pure culture.

G.What
are Some Ways that We Can Control Infectious Diseases?

1.Immunity - stimulating the body's own ability to
combat infection; from ancient times it was a recognized fact that people who suffered
from certain diseases never got them again; infection could produce immunity.

a.Immunization defined:produce immunity by providing exposure to altered
organisms that do not cause disease.

b.Jenner & Smallpox - observed that dairymaids
that contracted a mild infection of cowpox seemed to be immune to smallpox.He inoculated a boy with fluid from a cow pox
blister and he contracted cowpox; he then inoculated him with fluid from a smallpox
blister; the boy did not contract smallpox; the term vaccination came from vaccafor
cow.

c.The first vaccines:

1.)Pasteur's discovery? attenuated bacteria can produce immunity

2.)Attenuated defined - weakened virus or bacteria
that is unable to cause the disease (it was later discovered that killed microbes can also
produce immunity)

3.)What vaccines did Pasteur
develop?anthrax, rabies

2.Public
Hygiene

a.Improving sewage disposal.

b.Assuring a clean public water
supply.

c.Food preservation & inspection.

ex. Pasteurization - kills most microbes by exposing to heat.

d.Improving personal hygiene.

Semmelweiss & childbed fever

e.Developing
antiseptic techniques.

Lister & carbolic acid  he
developed the first aseptic techniques.

3.Chemotherapy

a.Who is the father of
chemotherapy?Paul Ehrlich - he discovered a drug treatment
for syphilis; he developed the guiding
principle of chemotherapy, which is selective toxicity(the drug must be toxic to the infecting microbe, but relatively harmless to the
hosts cells).

b.What was the first major class
of drugs to come into widespread clinical use?sulfa
drugs

c.Who discovered the first
antibiotic?Flemming discovered (penicillin); antibiotics
are antibacterial compounds produced by fungi and bacteria.